EGU2020-11854, updated on 09 Jan 2024
https://doi.org/10.5194/egusphere-egu2020-11854
EGU General Assembly 2020
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Aquifer parameter estimation for the Zhagu subcatchment (Tibetan Plateau) based on geophysical methods

Tuong Vi Tran1, Johannes Buckel2, Philipp Maurischat3, Handuo Tang4,5, Zhengliang Yu4,5, Thomas Graf1, Andreas Hördt2, Fan Zhang4,5, Georg Guggenberger3, and Antje Schwalb6
Tuong Vi Tran et al.
  • 1Leibniz Universität Hannover, Institute of Fluid Mechanics and Environmental Physics in Civil Engineering, Hannover, Germany (tran@hydromech.uni-hannover.de)
  • 2Institute for Geophysics and Extraterrestrial Physics, Technische Universität Braunschweig, Mendelssohnstraße 3, 38106 Braunschweig, Germany (j.buckel@tu-braunschweig.de, a.hoerdt@tu-braunschweig.de)
  • 3Institute of Soil Science, Leibniz Universität Hannover, Herrenhäuser Str. 2, 30419 Hannover, Germany (maurischat@ifbk.uni-hannover.de, guggenberger@ifbk.uni-hannover.de)
  • 4Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China (tanghanduo@itpcas.ac.cn, yuzhengliang@itpcas.ac.cn, zhangfan@itpcas.ac.cn)
  • 5University of Chinese Academy of Sciences, Beijing, China
  • 6Institute of Geosystems and Bioindication, Technische Universität Braunschweig, Langer Kamp 19C, 38106 Braunschweig, Germany (antje.schwalb@tu-bs.de)

The aquifers on the Tibetan Plateau (TP) constitute as origin for major river systems, which are supplying millions of people all over Asia. Increasing population and tourism activities leading to larger water consumption. Hence, water supply is getting increasingly important. The TP is a sensitive system and is noticeable reacting climate change. Past decades are marked with, increasing trends of precipitation, melting of glaciers and degradation of permafrost and have generally lead to rising water levels in lakes on the TP. To ensure future water supply, aquifer characterisation and future prognosis on groundwater behavior are therefore necessary. However, due to the remote character of the TP, knowledge according to hydrogeological parameter is scarce. The aim of this study is therefore to estimate a range for aquifer parameter based on geophysical methods. The Zhagu basin, situated in the Nam Co Lake basin (second largest lake on the TP), is used as a case study. This project is part of the International Research Training Group “Geoecosystems in transition on the Tibetan Plateau” (TransTiP), funded by the DFG.

During several field work campaign in July 2018, May 2019 and September 2019 disturbed sediment samples were taken and were analyzed for grain size distribution. Selected sediment layer in the laboratory were tested. Outcome of this analysis is the porosity for each selected sediment layer. Another measurement during field work has been conducted, namely electrical resistivity tomography measurements (ERT). To get better approximation of porosity and sediment characteristics, Archie’s Law is used as model to estimate those properties and later on to compare it to field and laboratory results. Two approaches are implemented (i) calculates the bulk resistivity based on known porosity from the laboratory and known conductivity of pore water measured during field work (ii) calculates the porosity with known conductivity of pore water and the bulk conductivity. For analysis saturated sediment layers were chosen.

The investigation shows that both approaches are largely applicable and leading to almost same results and trends of each sediment layer. The best percentage deviation of the modeled bulk resistivity results to the measurement in the field could be achieved by position D11 which is situated near the Nam Co Lake showing a deviation of around 7%. Inside the catchment the percentage deviation is largely increasing. However, the application of Archie’s Law in combination with field and laboratory measurements allows to construct a porosity ranges for future groundwater flow calibration. In addition, the results emphasising the zonation of the subsurface in (un)saturated zones due to the small amount of resistivity.

Sediment profiles, ERT measurements, observations, interpretation and conclusion including the comparison of simulated resistivity and simulated porosity to field resistivity and porosity based on laboratory analysis will be shown and discussed in the contribution.

How to cite: Tran, T. V., Buckel, J., Maurischat, P., Tang, H., Yu, Z., Graf, T., Hördt, A., Zhang, F., Guggenberger, G., and Schwalb, A.: Aquifer parameter estimation for the Zhagu subcatchment (Tibetan Plateau) based on geophysical methods, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11854, https://doi.org/10.5194/egusphere-egu2020-11854, 2020.

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